1. Field of the Invention
The present invention generally relates to a polyaxial fastener assembly, and spinal stabilization systems that include at least one polyaxial fastener. Embodiments of the invention relate to spinal stabilization systems that can be inserted into a patient preferrably using a minimally invasive surgical procedure. More particularly, embodiments disclosed herein relate to monoaxial fastener assembly created from a polyaxial fastener assembly. Embodiments of the invention relate to methods of assembling implant system components, methods of assembling stabilization systems and components, as well as the methods and tools employed for performing minimally invasive spinal stabilization procedures.
2. Description of Related Art
Bone can be subject to degeneration caused by trauma, disease, and/or aging. Degeneration can destabilize bone and affect surrounding structures. For example, destabilization of a spine can result in alteration of a natural spacing between adjacent vertebrae. Alteration of a natural spacing between adjacent vertebrae can subject nerves that pass between vertebral bodies to pressure. Pressure applied to the nerves can cause pain and/or nerve damage. Maintaining the natural spacing between vertebrae can reduce pressure applied to nerves that pass between vertebral bodies. A spinal stabilization procedure can be used to maintain the natural spacing between vertebrae and promote spinal stability.
Spinal stabilization can involve accessing a portion of the spine through soft tissue. Conventional stabilization systems can require a large incision and/or multiple incisions in the soft tissue to provide access to a portion of the spine to be stabilized. Conventional procedures can result in trauma to the soft tissue, for example, due to muscle stripping.
Spinal stabilization systems for a lumbar region of the spine can be inserted during a spinal stabilization procedure using a posterior spinal approach. Conventional systems and methods for posterolateral spinal fusion can involve dissecting and retracting soft tissue proximate the surgical site. Dissection and retraction of soft tissue can cause trauma to the soft tissue, and extend recovery time. Minimally invasive procedures and systems can reduce recovery time as well as trauma to the soft tissue surrounding a stabilization site.
U.S. Pat. No. 6,530,929 to Justis et al. (hereinafter “Justis”), which is incorporated by reference as if fully disclosed herein, describes minimally invasive techniques and instruments for stabilizing a bony structure in an animal subject. Justis provides a method for using an instrument to connect at least two bone anchors with a connecting element. The instrument is secured to the anchors and manipulated to place the connecting element in a position more proximate the anchors.
U.S. Patent Application Publication No. 20060084993, which is incorporated by reference as if fully disclosed herein, describes a spinal stabilization system including bone fastener assemblies having a bone fastener and a collar. The collar can be rotated and/or angulated relative to the bone fastener. Detachable members can be coupled to the collar to allow for formation of the spinal stabilization system through a small skin incision. The detachable members can allow for alignment of the collars to facilitate insertion of an elongated member in the collars.